Ions Alchemy Lesson V Chemistry Opener Chem Survey

Ions Alchemy Lesson V Chemistry

Opener: Chem Survey ¨ We’ve learned that, although difficult, an atom has the ability to accommodate changes in its nucleus. By losing or absorbing nuclear particles, an atom can completely change its identity! Do you think it’s possible for an atom to gain or lose electrons? Do you think it is an easier or more difficult process? Explain.

Lithium--Li ¨ 3 protons ¨ 3 electrons ¨ Loses 1 electron 3+ ¨ 3 protons/2 electrons ¨Li +1 “Oxidation Number” = used to indicate the charge of a particular ion

Beryllium—Be ¨ 4 protons ¨ 4 electrons ¨ Loses 2 electrons ¨ 4 protons/2 electrons ¨Be +2 4+

Magnesium--Mg ¨ 12 protons ¨ 12 electrons ¨ Loses 2 electrons ¨ 12 protons/10 electrons ¨Mg +2 12+

Boron--B ¨ 5 protons ¨ 5 electrons ¨ Loses 3 electrons ¨ 5 protons/2 electrons ¨B +3 5+

Aluminum--Al ¨ 13 protons ¨ 13 electrons ¨ Loses 3 electrons ¨ 13 protons/10 electrons ¨Al +3 13+

Oxygen—O ¨ 8 protons ¨ 8 electrons ¨ Gains 2 electrons ¨ 8 protons/10 electrons ¨O -2 8+

Sulfur--S ¨ 16 protons ¨ 16 electrons ¨ Gains 2 electrons ¨ 16 protons/18 electrons ¨S -2 16+

Chlorine—Cl ¨ 17 protons ¨ 17 electrons ¨ Gains 1 electron ¨ 17 protons/18 electrons ¨Cl -1 17 +

Nitrogen—N ¨ 7 protons ¨ 7 electrons ¨ Gains 3 electrons ¨ 7 protons/10 electrons ¨N -3 7+

Hydrogen--H ¨ 1 protons 1+ ¨ 1 electron ¨ Gains or loses 1 electron ¨H -1 or H +1 1+

How do you know…+ or -? ¨ All atoms have “noble gas envy”. ¨ Electronically speaking, they want to be like a noble gas – having 8 valence electrons. ¨ Atoms will either gain or lose electrons based on how ‘close’ they are to a noble gas. ¨ Ex: Oxygen has 6 valence electrons – do you suppose it is ‘easier’ for O to gain 2, or lose 6 electrons?

Making Ionic Compounds ¨ Positive (Metal) ion is always first. ¨ Number of ions in compound is shown with subscript. – Ca. Cl 2 ¨ If the number of ions in compound is 1, then a subscript is not needed. ¨ The total charge on the compound must be 0.

Making Ionic Compounds: +1 ¨Na -1 Cl and +1 -2 ¨Na and O

Practice 1 ¨Al 3+ -1 and Cl ¨Al. Cl 3

Practice 2 +2 ¨Cu. I 2 and -1 I

Practice 3 +1 ¨Ag 2 S and -2 S

Practice 4 2+ ¨Mg and -2 S ¨Mg. S (simplify!!)

Practice 5: For Experts!!! +3 ¨Fe and ¨Fe 2 O 3 -2 O

OK, What’s the Trick? ?